Blood glucose‐lowering effect of water and ethanolic extracts of Gynura procumbens (Lour.) Merr

Abstract

ABSTRACTAimGynura procumbens (Lour.) Merr. (GP) has drawn attention as an alternative drug for the treatment of diabetes mellitus. However, while most previous studies were done in diabetic mice to investigate the antidiabetic effect, this study investigated the blood glucose‐lowering action of GP in diet‐induced obese mice and clarified the possible mechanism of the glucose‐lowering action of GP in muscle and adipose cells.MethodsThe mice were divided into four groups (n = 6 in each group) depending on the diet that they received (i.e., the normal diet (ND), normal diet + 1% GP powder (ND + GP), high‐fat diet (HFD), high‐fat diet + 1% GP powder (HFD + GP) groups), and the oral glucose tolerance test (OGTT) was performed after one, three and five months. Immunocytochemistry revealed GLUT4 translocation in cells stably expressing myc‐GLUT4‐ECFP. The effect of GP extracts on the expression of GLUT4 and phosphorylation of 5'‐adenosine monophosphate‐activated protein kinase (AMPK) and Akt/protein kinase B (PKB) in C2C12 (muscle cell) and 3T3‐L1 (adipocyte) cells, was determined by western blot analysis.ResultsThe results showed that the significantly raised serum glucose levels in the HFD group were reduced following treatment with GP powder. Moreover, treatment with the GP extracts promoted GLUT4 membrane translocation more prominently in the C2C12 cells as compared to the 3T3‐L1 cells, whereas GLUT4 expression was significantly increased only in the 3T3‐L1 cells. AMPK phosphorylation was significantly increased by both extracts in both C2C12 cells and 3T3‐L1 cells.ConclusionThe findings of the present study reveal that GP may correct glucose intolerance and both the ethanolic and water extracts of GP have a blood glucose‐lowering effect, possibly via AMPK‐mediated signaling pathways in the muscle and adipose tissues.